<template>
  <div>
    <h3>父组件：{{ num }}</h3>
    <Child :value="num" @input="fn"></Child>
  </div>
</template>

<script>
import Child from './views/Child2'
export default {
  data () {
    return {
      num: 10
    }
  },
  components: {
    Child
  },
  methods: {
    fn (a) {
      this.num = a
    }
  }
}
</script>

<style>

</style>
